US9281755B2 - Inverter with coupled inductances - Google Patents

Inverter with coupled inductances Download PDF

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Publication number
US9281755B2
US9281755B2 US14/176,191 US201414176191A US9281755B2 US 9281755 B2 US9281755 B2 US 9281755B2 US 201414176191 A US201414176191 A US 201414176191A US 9281755 B2 US9281755 B2 US 9281755B2
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switch
inductance
inverter
intermediate point
switches
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US20140153298A1 (en
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Mehmet Kazanbas
Christian Noeding
Peter Zacharias
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SMA Solar Technology AG
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SMA Solar Technology AG
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M5/00—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases
    • H02M5/40—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc
    • H02M5/42—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters
    • H02M5/44—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac
    • H02M5/453—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M5/458—Conversion of ac power input into ac power output, e.g. for change of voltage, for change of frequency, for change of number of phases with intermediate conversion into dc by static converters using discharge tubes or semiconductor devices to convert the intermediate dc into ac using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/538—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a push-pull configuration
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M1/00—Details of apparatus for conversion
    • H02M1/0067—Converter structures employing plural converter units, other than for parallel operation of the units on a single load
    • H02M1/007—Plural converter units in cascade
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load
    • H02M3/1584—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load with a plurality of power processing stages connected in parallel
    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M7/00—Conversion of ac power input into dc power output; Conversion of dc power input into ac power output
    • H02M7/42—Conversion of dc power input into ac power output without possibility of reversal
    • H02M7/44—Conversion of dc power input into ac power output without possibility of reversal by static converters
    • H02M7/48—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M7/53—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M7/537—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters
    • H02M7/5387—Conversion of dc power input into ac power output without possibility of reversal by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only, e.g. single switched pulse inverters in a bridge configuration

Definitions

  • the present disclosure relates to an inverter for converting a direct current flowing between first and second input lines into an alternating current flowing between first and second output lines.
  • An inverter for converting a direct current flowing between two input lines into an alternating current flowing between two output lines performing as a current source, and comprising a series circuit made of a first high frequency switch, an inductance and a second high frequency switch, and connected between the two input lines is known from DE 196 42 522 C1.
  • one of the output lines is directly connected to one of the input lines.
  • An unfolding circuit of the known inverter comprises a first low frequency switch leading from the first intermediate point to the other output line, and a second low frequency switch leading from the second intermediate point to the other output line.
  • a third low frequency switch is provided between the second intermediate point and the one output line directly connected to the one input line.
  • the half-waves of the desired alternating current are formed.
  • the high frequency switch located on that side of the inductance from which the first rectifier diode leads to the first intermediate point is closed for those half-waves of the alternating current output at negative voltage between the output lines.
  • the first low frequency switch of the unfolding circuit is closed.
  • the two other low frequency switches of the unfolding circuit are open.
  • the two high frequency switches connected in series with the inductance are operated at a high frequency, and the second low frequency switch of the unfolding circuit connected between the first intermediate point and the other output line and the third low frequency switch of the unfolding circuit connected between the second intermediate point and the one output line connected to the one input line are closed.
  • Buffer capacitances are provided both between the output lines and between the input lines of the known inverter.
  • the buffer capacitance between the output lines is supplemented with an inductance in one of the output lines to make up an LC-filter for reducing a current ripple of the alternating current generated by the known inverter, i.e.
  • the photovoltaic generator may, however, be suitable to operate the photovoltaic generator either completely at negative or completely at positive electrical potential with regard to earth. Under certain conditions, like for example in order to limit the voltage with regard to earth, it may also be suitable to connect a center point of the photovoltaic generator to earth. This flexibility is not given with the known inverter.
  • An inverter comprising a series circuit made of a first high frequency switch, an inductance and a second high frequency switch and connected between two input lines is known from DE 10 2007 028 078 B4.
  • a first rectifier diode leads from one side of the inductance to one terminal of a voltage link, and a second rectifier diode of opposite blocking direction leads from the second side of the inductance to the other terminal of the voltage link.
  • the voltage link comprises a link capacitance; and a half-bridge made of two switches with anti-parallel diodes is connected between its terminals.
  • a center point of the half-bridge is connected to the L-conductor of a connected AC power grid via a grid choke.
  • the N-conductor of the AC power grid is connected to a center point of the link capacitance.
  • the switches of the half-bridge are operated at a high frequency to shape an alternating current driven by the link voltage of the voltage link.
  • a grid choke is essential to limit the current ripple of the alternating current fed into the AC power grid.
  • the known inverter with the pronounced voltage link is a typical representative of a voltage source inverter.
  • the inductance of its series circuit may be coupled to a further inductance which is connected to the voltage link via an additional diode and which also loads the voltage link.
  • one of its input lines may be freely selected for being connected to earth.
  • EP 2 244 367 A1 discloses a boost converter assembly connected between a photovoltaic generator and a voltage link at the input side of an inverter bridge.
  • the boost converter assembly comprises a plurality of boost converter units each comprising a controllable switch and an input inductor.
  • the plurality of boost converter units are connected in parallel and provide a DC link voltage at the voltage link that is higher than a DC voltage provided by the photovoltaic generator.
  • the individual boost converter units are operated in an interleaving mode.
  • US 2009/0251937 A1 discloses a circuit arrangement for converting a DC voltage present at DC voltage terminals into an alternating current which is supplied via AC voltage terminals.
  • the circuit arrangement has a first series circuit which is connected to the DC voltage terminal and comprises a first electronic switch and an inductor.
  • the circuit arrangement further comprises a plurality of second electronic switches.
  • One of the DC voltage terminals and one of the AC voltage terminals are connected to a neutral conductor.
  • the inductor is in the form of a twin inductor having two windings which are arranged tightly coupled to one another, wherein the first winding is connected in series with the first electronic switch and buffer-stores the energy produced via the electronic switch.
  • the two windings are each connected to the AC voltage terminal which is not connected to the neutral conductor via one of the second electronic switches.
  • One of these second electronic switches is closed during the half-waves of the alternating current with positive voltage between the AC voltage terminals, whereas the other of the second electronic switches is closed during the half-waves of the alternating current at negative voltage at the AC voltage terminals.
  • the first winding and the second winding of the inductor alternatingly provide the alternating current formed by operating the first switch at a high frequency half-wave by half-wave.
  • two series circuits each comprising a first electronic switch and an inductor are provided and connected in parallel to the two second electronic switches.
  • the first switches of the two series circuits are operated at an offset to have a more uniform flow of energy.
  • WO 2011/016449 A1 discloses a DC/DC converter comprising two groups of four switching elements.
  • the four switching elements of one of the two groups are arranged in two half-bridges between the input lines of the DC/DC converter, and the four switching elements of the other of the two groups are arranged in two half-bridges between the output lines of the DC/DC converter.
  • One center point of each half-bridge of the one group is connected to one center point of a half-bridge of the other group via a primary winding of a magnetic field cancellation type transformer, whereas the center point of the other half-bridge of the one group is connected to the center point of the other half-bridge of the other group via a secondary winding of the transformer.
  • one of the input lines is directly connected to one of the output lines.
  • the DC/DC converter is capably of varying boosting and bucking ratios and a bidirectional boosting-bucking operation.
  • the present disclosure relates to an inverter for converting a direct current flowing between first and second input lines into an alternating current flowing between first and second output lines.
  • the inverter comprises a first series circuit comprising a first switch switchable at a high frequency, a first inductance and a second switch switchable at a high frequency, and connected between the two input lines.
  • the inverter further comprises a second series circuit comprising a third switch switchable at a high frequency, a second inductance and a fourth switch switchable at a high frequency, and connected between the two input lines.
  • the first and second inductances are magnetically coupled.
  • the inverter further comprises a first rectifier diode leading from a first side of the first inductance to a first intermediate point, a second rectifier diode leading from a second intermediate point to a second side of the first inductance, a third rectifier diode leading from a first side of the second inductance to the first intermediate point, and a fourth rectifier diode leading from the second intermediate point to the second side of the second inductance.
  • the inverter also comprises an unfolding circuit connected to the first and second intermediate points and to the first and second output lines, and comprising switches switchable at the frequency of the alternating current.
  • FIG. 1 shows a first embodiment of the inverter of the present disclosure in an application for feeding electric energy from a photovoltaic generator into a single-phase AC power grid.
  • FIG. 2 illustrates a first switching state of the inverter according to FIG. 1 .
  • FIG. 3 illustrates a second switching state of the inverter according to FIG. 1 .
  • FIG. 4 illustrates a third switching state of the inverter according to FIG. 1 .
  • FIG. 5 illustrates a fourth switching state of a variant of the inverter of FIG. 1 supplemented with an buffer capacitance at its output.
  • FIG. 6 shows an embodiment of the inverter with regard to earthing the photovoltaic generator.
  • FIG. 7 shows another embodiment of the inverter with regard to earthing the photovoltaic generator.
  • FIG. 8 a variant of the inverter according to the embodiment of FIG. 1 comprising three instead of only two series circuits each made of two switches operated at a high frequency and of one intermediate inductance and connected between first and second input lines.
  • FIG. 9 shows a protective circuitry which can be connected in parallel to the unfolding circuit of the inverter according to any the previous figures.
  • FIG. 10 is a graph of the control signals for the switches of the inverter according to FIG. 1 for forming an alternating current output out of a direct current input.
  • capacitance is used to refer to one or more capacitors connected in parallel and/or series for providing an electric capacitance.
  • inductance refers to one or more inductors connected in series and/or parallel for providing an electric inductance.
  • the present disclosure relates to an inverter comprising a series circuit comprising a first switch switchable at a high frequency, an inductance and a second switch switchable at a high frequency, and connected between the first and second input lines; a first rectifier diode leading from a first side of the inductance to a first intermediate point, and a second rectifier diode leading from a second intermediate point to a second side of the inductance; and an unfolding circuit connected to the first and second intermediate points and the first and second output lines, and comprising switches switchable at the frequency of the alternating current.
  • an inverter Due to its properties similar to a current source, such an inverter is also referred to as a current source inverter.
  • the present disclosure relates to inverters for feeding electric energy produced by a photovoltaic generator into a single-phase AC power grid.
  • the present disclosure distinguishes between switches switchable at a high frequency which are also referred to as high frequency switches here without intending any limitation to a particular high frequency (HF) range, and switches switchable at the frequency of the alternating current which are also referred to as low frequency switches here.
  • the high frequency switches are configured for being suitably operated at a frequency in the range of 1 to some 10 kHz, whereas the low frequency switches are configured for being suitably operated at a frequency of about 500 Hz at maximum.
  • the low frequency switches are operated at a frequency of about 50 to 60 Hz.
  • “Suitably operated” means that the switches can be switched or operated at the respective frequency for an extended period of time without producing excessive power losses.
  • the inverter besides a first series circuit made of a first switch switchable at a high frequency, a first inductance and a second switch switchable at a high frequency, a further series circuit made of a third switch switchable at a high frequency, a second inductance and a fourth switch switchable at a high frequency is connected between the first and second input lines. Further, the first inductance of the first series circuit and the second inductance of the second series circuit are magnetically coupled.
  • a rectifier diode leads from a first side of the first inductance to a first intermediate point to which a further rectifier diode, which is also referred to as the third rectifier diode here, leads from a corresponding first side of the second inductance of the second series circuit; and a second and a fourth rectifier diode lead from a second intermediate point to corresponding second sides of the first and second inductance of the first and second series circuits, respectively.
  • a current flows between the first and second intermediate points whose direction is determined by the blocking directions of the first to fourth rectifier diodes and which—at the same time—is sine-shaped half-wave by half-wave by means of high frequency operating the switches switchable at a high frequency.
  • this high frequency is in a range of a few kilohertz.
  • This sine shape is provided nearly without current ripple because the current—despite being sine-formed—for example, by direct pulse width modulation, may flow through the alternatingly operated series circuits nearly without interruption.
  • an unfolding circuit connected to the first and the second intermediate point has only to forward this direct current with alternating polarities to the output lines half-wave by half-wave. No filtering of this alternating current is required.
  • the present disclosure despite the second inductance in the second series circuit between the input lines—results in a reduced building size.
  • an LC-filter and thus a big grid choke can be completely avoided.
  • the smaller inductances of the two series circuits may each be made much smaller than an inductance of a single series circuit between the input lines.
  • the effective frequency is increased by a factor of two with regard to the actual switching frequency due to the magnetic coupling.
  • the size of each inductor may be reduced by at least 30% as compared to individual circuitries without magnetic coupling.
  • the inverter of the present disclosure does not only work without a capacitance of an LC-filter but also without a voltage link capacitance. However, providing a small smoothing capacitance prior to or behind the unfolding circuit which provides for additionally smoothing the shaped alternating current may be advantageous under certain conditions. Principally, however, the inverter of the present disclosure has a buffer capacitance between its input lines.
  • the high frequency switches of the inverter of the present disclosure are both subjected to a lower voltage load and a lower current load as compared to an inverter only comprising one series circuit comprising an inductance between the input lines.
  • the dimension of the high frequency switches may be kept smaller which at least partially compensates for the additional high frequency switches.
  • the switches switchable at the frequency of the alternating current of the unfolding circuit may be made as backflow blocking switches like for example low-cost grid thyristors due to the avoided output side inductance.
  • so-called normally-on silicon carbide (SiC) semiconductor technology may be used with the high frequency switches as—due to the two current branches via the two series circuits between the input lines—both the load to the switches and the short-circuit risk are reduced.
  • either one of the first and second input lines or any other point at the input side, like for example a center point of a photovoltaic generator connected to the input lines may be earthed as desired.
  • the earthed input line may be directly connected to an also earthed output line. This, however, is not essential for the function of the inverter of the present disclosure.
  • the number of the series circuits of two high frequency switches and an intermediate inductance each connected in parallel to each other between the input lines is not limited to two.
  • there may, for example, be a third series circuit comprising a fifth switch switchable at a high frequency, a third inductance and a sixth switch switchable at a high frequency, and connected between the two input lines.
  • the first inductance, the second inductance and the third inductance are magnetically coupled, and a fifth rectifier diode leads from a first side of the third inductance to the first intermediate point, and a sixth rectifier diode leads from the second intermediate point to a second side of the third inductance.
  • the first side from which the fifth rectifier diode leads to the first intermediate point points towards the same first input line as the first sides of the first and second inductances from which the first and second rectifier diodes lead to the first intermediate point. Similar rules apply to the second sides of the inductances to which the second, fourth and sixth rectifier diodes lead from the second intermediate point, and which point towards the same second input line.
  • the direction in which the respective rectifier diode “leads” here refers to its conducting direction, and that the conducting directions of the rectifier diodes are each oriented in such a way that a current flux from the input lines to the output lines is only possible through the respective inductance. Even with a closed neighboring high frequency switch no direct flow from the neighboring input line is possible as such a flow would be blocked by the rectifier diodes.
  • the unfolding circuit may particularly be a commutator circuit comprising a full bridge between the first and the second intermediate points, and it may correspondingly comprise a first switch switchable at the frequency of the alternating current and connected to the first intermediate point and to the first output line, a second switch switchable at the frequency of the alternating current and connected to the second intermediate point and to the first output line, a third switch switchable at the frequency of the alternating current and connected to the first intermediate point and to the second output line, and a fourth switch switchable at the frequency of the alternating current and connected to the second intermediate point and to the second output line.
  • the low frequency switches of the unfolding circuit may be operated by a controller which also operates the high frequency switches of the series circuits between the input lines. It is also possible to provide a control circuit for line commutation of the switches of the unfolding circuit by means of an alternating current grid connected to the output lines. Such line commutated unfolding circuits are generally known.
  • the inverter may nevertheless comprise a protective circuitry connected between the first intermediate point and the second intermediate point.
  • the protective circuitry may comprise two series circuits of two oppositely oriented rectifier diodes each connected in parallel, the rectifier diodes of the two series circuits comprising opposite blocking directions, and intermediate points of the two series circuits being connected to each other via a capacitance and a varistor connected in parallel.
  • This protective circuitry provides a dynamic clamping function which is both effective in the direction of the alternating current grid and in the direction of a photovoltaic generator connected to the input lines of the inverter of the present disclosure.
  • FIG. 1 shows an inverter 1 for feeding electric energy from a photovoltaic generator 2 into a single-phase alternating current grid 13 .
  • the negative terminal of the photovoltaic generator 2 is earthed just as a zero conductor of the AC power grid 13 .
  • the photovoltaic generator 2 is connected to input lines 3 and 4 of the inverter 1 .
  • a buffer capacitance C provided by one or more individual capacitors is connected between the input lines 3 and 4 .
  • a first series circuit 5 and a second series circuit 6 are connected between the input lines 3 and 4 .
  • Each series circuit 5 and 6 is made of two high frequency switches S 1 and S 2 , and S 3 and S 4 , respectively, and an inductance L 1 and 2 , respectively, arranged between the two switches S 1 and S 2 , and S 3 and S 4 , respectively.
  • the two inductances L 1 and L 2 are magnetically coupled, e.g. made as two windings on a common core.
  • a first rectifier diode D 1 and a rectifier diode D 3 which is called the third rectifier diode here lead to a first intermediate point 7
  • a second rectifier diode D 2 and a fourth rectifier diode D 4 lead from a second intermediate point to the respective other side of the inductances L 1 and L 2 .
  • the blocking directions of the rectifier diodes D 1 and D 4 are oriented in such a way that even if the neighboring switches S 1 to S 4 switchable at a high frequency are closed, no current may flow directly from the input line 3 or 4 connected to the intermediate points 7 and 8 but only through the respective inductance L 1 or L 2 .
  • an alternating current may be formed between the intermediate points 7 and 8 .
  • the current may be formed to a sine-shape half-wave by half-wave.
  • the voltage present between the two input lines 3 and 4 may be boosted here.
  • the input side circuitry part 9 of the inverter 1 reaching up to the intermediate points 7 and 8 may in principle also be used separately as a buck-boost-converter, i.e. as a DC/DC converter which may boost or buck an input voltage.
  • this input side circuitry part 9 primarily serves for sine-shaping the direct current between the intermediate points 7 and 8 half-wave by half-wave, and the output side unfolding circuit 10 of the inverter 1 feeds this direct current at a polarity alternating half-wave by half-wave via output lines 11 and 12 into the AC power grid 13 .
  • the unfolding circuit 10 comprises a full bridge between the intermediate points 7 and 8 including switches S 7 to S 10 switchable at the frequency of the alternating current.
  • the output lines 11 and 12 are connected to mid-points of half-bridges of the full bridge in a known way.
  • the switches S 7 to S 10 of the full bridge may be guided directly, i.e. operated by the alternating grid voltage.
  • FIGS. 2 to 5 different switching states and the resulting current paths through the inverter 1 according to FIG. 1 are shown which are activated for forming the direct current having a sine-shape half-wave by half-wave between the intermediate points 7 and 8 .
  • the switches S 1 and S 2 of the series circuit 5 are closed.
  • the inductance L 1 is energized.
  • the two switches S 3 and S 4 of the second series circuit 6 are open and thus not depicted here.
  • the second inductance L 2 connected between the two switches S 3 and S 4 is de-energized via the diodes D 3 and D 4 .
  • the current through the second inductance L 2 is maintained by the magnetic coupling to the first inductance L 1 and by its previous energization.
  • FIG. 4 the opposite of the situation in FIG. 2 is present with regard to the series circuits 5 and 6 .
  • the switches S 3 and S 4 are closed, whereas the switches S 1 and S 2 are open and are thus not depicted here.
  • the inductance L 2 is energized. Current flows from the inductance L 1 into the AC power grid 13 via the diodes D 1 and D 2 ; and the current is maintained both by the magnetic coupling with the second inductance L 2 and due to the previous energization of the inductance L 1 .
  • FIG. 5 shows the situation when all four high frequency switches S 1 to S 4 according to FIG. 1 are closed to simultaneously energize both inductances L 1 and L 2 for boosting the input voltage.
  • a current flowing in the direction towards the AC power grid 13 may only be maintained, if an additional output side capacitance C A is provided which is otherwise not needed in the inverter 1 according to FIG. 1 .
  • FIG. 6 shows such a connection 14 between the output line 12 and the input line 3 with a dashed line.
  • the entire photovoltaic generator 2 is on a negative electric potential with regard to electric earth as its positive terminal is earthed.
  • the entire photovoltaic generator 2 is on a positive electric potential with regard to earth.
  • one of these electric potentials may be advantageous for a long lifetime of the photovoltaic generator 2 .
  • the optional connection 14 indicated with a dashed line extends between the output line 12 and an intermediate point 17 of the photovoltaic generator 2 which is earthed here to, for example, limit the maximum voltages in the area of the photovoltaic generator with regard to earth to half of a PV-voltage provided by the photovoltaic generator.
  • FIGS. 6 and 7 together with FIG. 1 , demonstrate the degrees of freedom which are given when using the inverter 1 , both with regard to earthing in the region of its input lines 3 and 4 and with regard to earthing in the region of its output lines 11 and 12 .
  • FIG. 8 illustrates the option to increase the number of series circuits 5 and 6 by further series circuits each consisting of two high frequency switches and an intermediate inductance.
  • one further series circuit 15 made of two high frequency switches S 5 and S 6 and of an inductance L 3 connected in between and magnetically connected to the inductances L 1 and L 2 of the series circuits 5 and 6 is provided here. From that side of the inductance L 3 pointing to the switch S 6 which is connected to the input line 4 , a fifth rectifier diode D 5 leads to the intermediate point 7 , whereas a sixth rectifier diode D 6 leads from the intermediate point 8 to the other side of the inductance L 3 .
  • FIG. 9 illustrates a protective circuitry 16 between the intermediate points 7 and 8 which is connected in parallel to the unfolding circuit comprising the switches S 7 to S 10 .
  • the protective circuitry 16 comprises a first series circuit of two opposing rectifier diodes D 7 and D 8 and a second series circuit of two opposing rectifier diodes D 9 and D 10 connected in parallel.
  • the rectifier diodes D 7 and D 9 on the one hand and D 8 and D 10 on the other hand comprise blocking directions opposing each other.
  • the center points 18 and 19 of the two series circuits of the rectifier diodes D 7 and D 8 on the one hand and D 9 and D 10 on the other hand are connected via a capacitance C S and a varistor 20 connected in parallel. If overvoltages occur between the intermediate points 7 and 8 which may not be compensated for by the capacitance C S the varistor 20 becomes conductive and compensates the overvoltages by a direct flow of current between the intermediate points 7 and 8 .
  • FIG. 10 illustrates the control signals for the high frequency switches S 1 to S 4 of the series circuits 5 and 6 of the inverter 1 , which are operated at a high frequency here, and the control signals for the low frequency switches S 7 to S 9 of the unfolding circuit 10 , which are operated at the frequency of the alternating current AC.
  • the shaping of the alternating current into sine-shaped half-waves is effected by pulse width modulation at an equiphased operation of the switches S 1 and S 2 which is inversely phased with regard to an equiphased operation of the switches S 3 and S 4 .
  • FIGS. 2 and 4 are used here.
  • the half-waves of the direct current between the intermediate points 7 and 8 are then forwarded to the output lines 11 and 12 of the inverter by operating the switches S 7 to S 10 in pairs as in a commutator so that the desired sine shaped alternating current AC flows between these output lines 11 and 12 .

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Inverter Devices (AREA)
  • Control Of Electrical Variables (AREA)
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DE102011052768.0 2011-08-17
DE102011052768 2011-08-17
DE102011052768A DE102011052768A1 (de) 2011-08-17 2011-08-17 Wechselrichter mit gekoppelten Induktivitäten
PCT/EP2012/065193 WO2013023936A1 (fr) 2011-08-17 2012-08-02 Onduleur avec inductances couplées

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WO2013160718A1 (fr) * 2012-04-26 2013-10-31 Freescale Semiconductor, Inc. Alimentation électrique à mode de commutation
WO2015085926A1 (fr) * 2013-12-10 2015-06-18 Neal George Stewart Régulateur perfectionné de tension alternative de type série haute fréquence
US10230242B2 (en) * 2014-10-10 2019-03-12 Edge Electrons Limited Maximizing energy savings by utilizing conservation voltage reduction with adaptive voltage control and peak demand reduction at point of use
CN105141160A (zh) * 2015-08-24 2015-12-09 苏州市博得立电源科技有限公司 一种车载电源光伏逆变器
CN111654183B (zh) * 2020-06-12 2021-10-29 深圳英飞源技术有限公司 一种直流-直流变换装置及其控制方法

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US20140153298A1 (en) 2014-06-05
EP2745391A1 (fr) 2014-06-25
DE102011052768A1 (de) 2013-02-21
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CN103765754A (zh) 2014-04-30
CN103765754B (zh) 2016-06-01
WO2013023936A1 (fr) 2013-02-21

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